Automatic oil burner



Nov. 19, '1929.

ZZZ

OIL.

G. D. SUNDSTRAND AUTOMATIC OIL BURNER Original Filed Dec. 2, 1925 8Sheets-Sheet 1 171116171751 v5' d d, 6, ,3 an 5 ran Nov. 19, 1929. e. D.SUNDSTRAND AUTOMATIC OIL BURNER Original Filed Dec. 2, 1925 8Sheets-Sheet 2 New Nov. 19, 1929. G. D. SUNDSTRAND AUTOMATIC OIL BURNER8 Sheets-Sheet 5 Original Filed Dec. 2, 1925 QR Nu Q NNN kw N 1929. G.D. SUNDSTRAND 1,735,911

V AUTOMATIC OIL BURNER 7 Original Filed Dec. 2, 1925 8 Sheets-Shet 4Nov. 19, '1929. cs. D. SUNDSTRAND AUTOMATIC OIL BURNER Original FiledDec. 2, 192's 8 Sheets-Sheet 5 hand, M

Nov. 19, 1929. G. D. SUNDSTRAND 1,735,911

AUTOMATIC OIL BURNER Original Filed Dec. 2, 1925 8 Sheets-Sheet 6 j I@'5 /260 FRONT 265 v/Ew. a, r.

PHI/V.

Nov. 19, 1929. G. D. SUNDSTRAND 1.735,-911

AUTOMATIC OIL BURNER Original Filed Dec. 1925 8 SIieQtS -Sheet 7Patented Nov. 19, 1929 UNITED STATES GUSTAF DAVID SUNDSTRAND, OFROCKFORD, ILLINOIS, ASSIGNOR TO SO'NDSTBAND ENGINEERING COMPANY, OFROCKFORD,

PATENT orrlcs ILLINOIS, A CORPORATION OF- ILLINOIS AUTOMATIC OIL BURNERApplication filed December 2, 1925,8er1 a1 No. 72,634. Renewed May 24,1928.

The present invention relates generally to oil burners and especially tothe type of burner which is usually associated with automaticcontrolling mechanism. The invention re- I 5 lates more specially tothat type of self-con trolled burner which is adapted to mamta-m' apredetermined degree of heat within a very narrow range of temperaturewlthout the mtervention of an attendant, unless some emer- 1 gencydefect arises, in which instance the burner is adapted to becomeinoperative and non-responsive to the startm control.

The general object of the inventlon is to provide a noiseless andefficient combustion, and a suitable mechanism for furnishing oil andair for combustion, together with an automatic controlling systemproviding perfect control over the burner in normal and in emergencyconditions. t

Another object is to provide an 01l:bllIIllng apparatus which is capableof burnlngrelatively heavy fuel oil, as, for example, 011 of 18 to 24Baum gravlty.

Still another object of the invention is the provision of a fuel controland. delivery system which ensures that no oil remains 1n the nozzle onshutting off the supply thereto, thereby preventing the. nozzle fromaccumulating residues therein by the actlon of heat upon oil whichotherwise would be reta ned within the nozzle. A further object is theprovlsion ofa mechanical control device operated directly from themoving burner parts and disengagetrolled clutch mechanism. 0

It is another object of the invention to pro- 'vide a device which willrecycle the burner through stopping and starting actionswhen its normaloperation dllIlIlg'COlTlbllStlOIt 1s prevented by an interruption 1n thehue power.

A further ob ect 1s to provide a control device responsive to a type ofthermostat WhlCll requires a small current through the thermostat duringburner operation, the control device being arranged so that a defect 1nthe thermostat circuit is effective to shut off the burner.

Still another object of the lnvention 15 to able therefrom by athermostatically conprovide, in combination with a normally con tinuouslacting ignition means, a device capable 0 cutting out the ignition atwill at a time onl when it is not absolutely necessary, which evice isoperative automatically to place the ignition means' again intooperation when its function is required. Various other objects andadvantages of the invention will be appa'rentafter an understandin ofthe invention as hereinafter explained ully and in detail, withreference to a preferred embodiment of the invention shown in theaccompanying drawings primarily for thepurpose of explanation.

The preferred embodiment of the invention comprises a nozzle, a burnerbowl, an ignition means, a motor, a blower, an air pump, means forsupplying oil under pressure, a control mecha ism, and a controlledclutch connection beween the control mechanism and the dri ing power, athermostat for starting and stopping the 'burner through the controlmechanism, and certain safety devices and constructions which avoid theusual and the emergency hazards ,of burneropera tion. The various safetyunits include a shut-off mechanism operated by an accumulation ofunconsumed oil, a heater control which stops operation of the burnerwhen excessive heat is produced regardless of the temperature ofthenormal controlling thermostat, a recycling device which causes theburner to pass through the igniting and starting actions incase there isan interruption in the line power during the operation of the burner,and a cut-out device which operates to stop the burner when there is adefective circuit to the controlling thermostat or in any other circuitsessential to the proper control of the burner. 3

Alt ough the foregoing enumeration of the parts of the burner refers tocertain devices, mechanisms or constructions having different functions,it is to be understood that these parts are not independent partsassembled togetherinto an operative unit, but they are ratherindividually active constructions having many parts in common which haveoverlapping and dual functions. This results from the provision ofsimple structural scribed. One familiar with the art will rea'dused,itis to electrically operated devices.

Although the various functionalunits may overlap in construction inthecombinations lbe understoodjthat'the following description ofan'exmplary or preferred embodiment of the accompanying drawings-is notto be construed as a limitation of the inventlonto the form hereindislosed and hereinafter deily conceive of other arrangements andalternative constructions of the functional units Therefore thefollowing description is to be taken merely as explanatory of theinvention, the scope of which is determined by the appended claims. f 1

In the accompanying drawings,"F1gure 1 1s a front elevation of anapparatus embodying the features of my invention.

Fig. 1 illustrates an alternative arrangement for forcing oil to thenozzle.

Fig. 2 is a plan view of the form of apparatus shown in Fig. 1, partsbeing broken away to shorten the view.

Fig.- 2* is a fragmental view illustrating an adjustable air intake forthe blower.

Fig. 3 is a side elevation of the apparatus shown in Fig. 2, parts beingbroken away to shorten .the view.

Fig. 3 is a detail view of a safety device.

operated by the weight of unconsumed oil. Fig. 3 is a section on lineb-b of Fig. 3

- Figs. 4 and 5 are sectional views illustrating the air pump andrelated parts.

Fig. 6 is a vertical sectional view of a valve mechanism for controllingthe flow of oil and air to the nozzle.

Fig. 7 is a'sectional view illustrating the nozzle and the igniter. v,Fig. 7 is a horizontal sectional view of the igniter. v Fig. 8 is afront view of the control mechanism, the view being taken approximatelyin the plane of line 88 of Fig. 9 and line 88 of Fig. 10. The parts arein position shown in'Fig. 11.

Fig. 9 is a plan view of the control mechanism.

Fig. 10 is a vertical sectional view of the control mechanism takenapproximately in the plane of line 10!10 of Fig. 9.

' Flg. 10 is a detail view of a certain detent. Fig. 10" is a fragmentaldetail view of the ignition switch and the lever on which it is mounted.A

Fig. 11 is a vertical sectional view of the control mechanism takenvapproximately in the plane of line 11-11 of Figs. 8 and 9.

Fig. 11 is a detail view of one of the elements of the clutch throughwhich the control mechanism is driven.

Fig. 11 is a detail view of a certain bell the invention as illustratedin F stat circuits. 1

R f rr ng t g 2 d 3 t ere is crank member comprised in the controlmechanism a Fig. 12 is a diagram ofthe motor circuit and the ignitioncircuit, showing also the transformers that supply current to the roomthermostat circuitsu Fig, 13 illustrates diagrammatically. threedifferent positionsof the room thermostat.

Fig. 14is a diagram shown a burner unit mounted on a base 10 and adaptedto be placed before a boiler or other heater shown in part anddesignated 11. The-upper or combustion chamber door 12 of the heater hasan opening therethrough which is covered by a plate 13 on which cerofthe room thermotain of 'the burner parts are mounted. The

general arrangement of the burner parts in the heater is such as tospray a mixture of oil and air from a nozzle14 located high in thecombustion chamber down into a bowl 15 herein shown as circular, intowhich a tangential stream of air'is forced by a blower 16, thearrangement being such that the oil spra' follows generally the pathindicated by t e dotted line 17 (shown offset in Fig.

3), in order that the oil spray may impinge on the entering stream ofair in the bowl in -the vicinity of the point 18 (Fig. 2). Of-

course, it'is to be understood that the spray spreads outwardly from thenozzle and-is carried or dragged away from a true conical path by thewhirling air and gases.

The blower 16 comprises, in the present instance, a casing 20 enclosinga fan 21 (Fig. 2) carried on a shaft 22. A coupling 23 is provided forconnectingthe shaft 22 to a motor shaft 24. Any typeof motor such asthat indicated at 25 may thus be used. As.

shown in Fig. 1, a suitable adjustable motormounting-platform isprovided. This comprises a vertically adjustable leg'26 fitting in asocket 27 on the base 10 and held by a set screw 28. The leg 26 carriesa platform or shelf 30 upon which the motor 25 is bolted. The fan casinghas a tangential outlet 31 (Fig. 3) leading into a suitable conduit 32which enters at the bottom of the heater 11 for connection to the bowl15. The inlet to the fan is through a central opening 33 (.Fig.

2) about the motor shaft 24, and it is partially closed by an adjustablecrescent shaped damper 35 movable about its pivotal clamping screw 36.The casing 20 is supported for limited rotary adjustment on the axis ofthe fan shaft. This facilitates locating the burner with reference toany heater by permitting the outlet 31 to be moved circumferentially ofthe fan and to permit its being telescoped, if desired, into the conduit32. Adjacent the blower casing 20 and on the base 10 is a' frameworkcomprised of various housings or casings and generally designated by thenumeral 40. The main shaft 22 extends through the framework and servesto provide power for operating pumping means.

for air and oil,-or for air alone, and for driving acontrol mechanismassociated with the electrical control features or safety devices abovealluded to. On the extreme .end of the main shaft 22 outside of theframework there is shown a centrifugal oil pump 41 which may be used forsupplying oil to the burner, the

' details of the pump, however, forming no part of this invention. Thisposition makes the oil pump readily removable and it can thus easily beattached or dispensed with .when not desired without mechanicaldifficulty. p

The air pump involves parts moving relatively slowl compared to thespeed of the motor 25; Tie first speed reduction is obtainedfrom a worm42 (Fig. 4) on the main shaft 22 meshing with a worm wheel 43 on atransverse countershaft 44 within the housing. The other end of theshaft 44 carries a disk 45 carrying a crank-pin 46 operatively connectedto anair pump 47.

Because of the extensive useof oil burnersof this general type fordomestic purposes, it is desirable to use an air pump construction whichminimizes the danger of break-down or' of failure of the pump. Suchfailures would leave the housewithout heat awaiting the return of thehouseholder or the arrival of a service man to remedy the defect.terruption of the burner should be minimized. The reciprocatoryoscillating air pump of the type herein described is preferred becauseof its simplicity of construction, its durability, and its minimumnumber of moving or wearing parts, and also because of its slower actioncompared to the usual rotary pump. Heretofore rotary air pumps whichhave been used employ sliding vanes and the vanes are subject to greatpiston, these parts are eliminated and by the provision of anoscillatory pump valve mechanism is also eliminated whereby to simplifythe construction.

Within the housing 40 there is a depending web or supporting wall inwhich there are two vertical passages formed which extend throu h thetop 61 of the housing. The

I passage 62 (Fig. 5) is closed by a plug 62 screwed into the top 61 andhas a laterally communicating hole or port 63 opening into the space 64within the hous ing beneath the top 61. Port 63 is an air inlet port forthe pump. The left hand passage 65 (Fig. 5) opens through the top 61 andis screw-threaded as shown at 66. This opening is the outlet for the airpump 47 Both passages 62 and 65 are closed at the Hence, the likelihood.of such in end of the wall'serves as a bearing for a trunnion 68 havingat one end a pump cylinder 69 and at the other a nut 70. The cylinderand the lower right face (Fig. 4) of the web 60 havefinishedsuperimposed plane bearing surfaces indicated at 71. Inlet andoutlet ports connect the interior of the cylinder and the passages 62and 65, there being in .thecylinder a shifting port to registeralternately vwith the inlet and outlet ports in the wall 60. The inletports in the web 60 are designated as 72 and 73 and are connected to theinlet passage 62 by suitable passages 7 4 in the interior of said web.The outlet ports 75 and 76 are connected by passages 77 to the outletpassage 65. The inlet port 72 and the outlet port 75 are arranged tocommunicate alternatively with a port 78 in the cylinder. v Similarlythe inlet port 73 and the discharge port 76 communicate alternativelywitha port 79 in the pump cylinder. A piston rod 80 slides in, longbearings 81 at each end of the cylinder. The upper end of the piston rodis connected to the crank pin 46.

Situated on the rear part of the oil burner framework is an adjustablestandard 86 (Fig. 3) held in a socket 87 by a screw 88. The upper end ofthe standard carries a nozzle structure and ignition means which projectthrough the door 12 of the heater. In the plate 13 on the door 12 is anobservation hole providedwith a hinged closure 89 (Fig.

1). On the plate 13 is a nozzle-carrying plate 90 which is so mounted asto swing angularly for the purpose of adjusting the angular direction ofthe spray to cause it to impinge at the proper point in the bowl 15. Theplate 90 swings about the axis of a sleeve 91 and is provided witharcuate slots 92 and clamping screws-93. The sleeve 91 is integral withthe plate 13 and a bracket 94 (Figs. 3 and 7 secured to the standard 86.

The nozzle structure comprises a suitable means arranged to receive asupply of air and a supply of oil, the air being used to spray theoil.by aspiration, t hat is, the differential pressure between theatmosphere and the oil is in efiect increased by the aspirating effectof the escaping air. In the present nozzle, however, the reverse istrue, the pressure of the air serving to repress the flow of oil underits own applied pressure.

The nozzle construction in the present instance comprises a cast head101 (Fig. 7) having an axial threaded bore 102 enlarged at its lower endto form a chamber 103 and there screw threaded to receive a nozzle tip104. The latter has a conical recess 105 formed fromthe inner facethereof and a short narrow cylindrical delivery hole 106. A threadedplug 107 screws into the upper portionof the bore 102' and is providedwith Ordinarily nozzles of this type spray a tapered or rearwardlyconical end 108 narrower than the taper 1051;} The-plug 107i's-provide'd with an ,annularicliannel 109 "and passages .1110 whichextend from the chafniel to the axial bore 111 ofthe "plu g,- t hepassage 111 opening atithe 'tapered" 'end 108.- The head 101 has an oilinlet 112 andangair inlet 1'13 communi'cat; ing're'spectively with theoil channel-109 and the air chamber 103'. Both'conical parts areprovided 'wi h right f'rustal bases which are in the present instance ofthe'same'v diameter as indicated at 114 and 114 Thus, the plug 107 maybe screwed'tightly against the nozzle cap andwhen withdrawn therefrom itterminates' at successively greater cross section'- al areas of theconical recess: 105 and .may therefore be Subjected to differentpressures according to itsposition. There will',a of course, be onepointw ere the annular. space 115.at thebase 114-bet" een the twotapered surfaces willbe equal in areato the opening 106. This isreferred to position. By movingthe plug forward from this position thisannular space becomes the issuing orifice for the air and by movingitthe opening 106 becomes the issuing orifice. InI'the latter case'thetipof the plug will be subject to the air pressure within the space 115and this air .pressure will repress the oil. 'When the opening 106 isthe air orifice adjustment of the plug 107 will not vary thepressure onthe oil exerted by the air. However, when the plug is in a positionforwardof the transitional position the annular space 115 becomes theissuing orifice, and the pressure willbe less than the applied airpressure, thus permitting more oil to flow as the plug 1S II1OVQ(1forwardly. It should be remembered, however, that the exact conditionsabove dcscribedare in practice varied, because a' portion of the orifice106 is occupied by the stream of oil thus reducing its cross sectionalarea available for air delivery. The construction therefore provides foran adjustment of the positionof the plug 107 to vary the air pressurebucking the oil pressure and yet the differential pressure under whichoil is emitted Wlll be small. This enables the maintenance of a high oilpressure in the system without the necessity ofemitting oil under a highpressure into the fire box. It further permits adjustment of thedifferential oil pressure at the nozzle without adjusting thepressure-producin g mechanism. The nozzle 14 is mounted on an extension118 of the plate 90. Oil and air pipes 119 and 120 coupled to conduits121 and 122, respectively, extend through the portion 118.

The flow of air and oil to the nozzle is controlled by a valve structurewhich has a'novel arrangement particularly related to the nozzle justdescribed. The whole oil burning system herein described is of a typeadapted to be frequently shut 011 and turned on to maintain an eventemperature. Upon shutting as the transitional off the supply of-oil tothe nozzle as is ordinari'ly one in other. burners, there will reemain-in the'nozzleLaJcertain quantit of oil. Although the combustion, inthe fire ox will cease at the {same time, "there is ahiglrdegree of heatin the firev box which soon heatsup the nozzle. Ordinarily the flow;- ofoil and'air I through the, nozzle keeps it relatively cool, but when theoiland air are shut 011 it is immediately subjected to heating actionwithout a; cooling action and-will become hotter than when it is in usewith combustion in the fire box. The-efiect of increased heat'on thenozzle would ordinarily serve to evaporate the fuelremaining thereinleaving tar or residues in the nozzle which may carbonize therein. Thiswould soon choke the nozzle, 7

making it ineffective and requiring. that: itbe cleaned frequently. Toavoid this I provide a means for blowing out the residual oil in thenozzle upon shutting off the oil supply.

This is preferably'done by blowing out also theoil l1ne leadin tothenozzle so that there 1s no creeping of oil therefrom into the nozzle. InFig. 6 a construction is disclosed which 18 in eflecta two-wa ."valveconnecting the nozzle 011 llne 121 eit er'with theroil supply or wlth anair supply. The valve structure comprises a casting 125 into which theoil and air conduits 121 and 122 are connected. 011 and air entry ports126 and 127 are also prov1ded,there beingin the present instance twoopposing posts 126 for oil and one port 127 for air on-(gye sides of thevalve. structure. Butone used according to the desired connections madein the apparatus. The ports open respectively into an oil passage 128and an air passage 129. In Figs. 1 and 2 it will be observed that oneoil port is closed by a plug 130, while the other oil. portis connectedto an oil conduit 131 extending from the oil pump ,41. An air supplypipe 132 '(Fig. 3) 1s connected into the air port 127. The valve casing125 has a tubular stem 133 by which it is mounted in the part 1351 onthe housing 10. The valve casing125 is bored at 137 in continuation ofthe bore of the stem 133. In the lower portion of thebore 137 is fixed abush ng 137. The upper end of the bore 137 15 enlarged at 138,andscrew-threaded plugs139 and 140 are provided for the ends of the .twoportions of different diameters. The plug 139 closes the passage at theoutside of the casing, while the plug 140 serves as-a valve sea beingprovided'with an opening liil therethrough so that oil may pass. The 011passage 128 leads into the chamber 138, and a port 142 leads from thebore 137 to the 011 conduit 121. A constantly open duct 143 connects thepassage 129 to the air conduit 122. A valve means is provided which isoperable to shut off the oil to the oil conduit and to permit the entryof air thereto to blow l the opposing ports need be i out the oil. Avalve stem 144 slides in the The oil port 142 leading to the nozzle isbe-' tween the oil supply port 141 and the air supply port-146. On saidvalve stem is a valve head 147 which is slightly smaller than the borein order to leave an air space 148 about the head from end to end. Thehead 147 has a tapered seat-and-plug end 149 which closes the oilpassage 141 in the uppermost position of the valve stem; and it has asimilar end 150 which closes the air port 146 in the lowermost positionof the valve stem.

To operate the valve a movable plunger 4 151 acts on the valve stem 144through an impositive connection including spring means. A socket member152 is fixed on the end of the valve stem 144, and in its socket an.expansible spring 153 is placed. Plunger 151 operates to move the stemby compression through the spring 153. The valve stem 144 is suitablypacked and guided in the bottom of the extension 133 as indicated at 154Be tween the stufiing box 154 and the socket member 152-is a second andlighter spring 156 which normally tends to compel the socket member 152to follow the plunger 151 when the latter is withdrawn, whereby to openthe oil valve.

To regulate the supply of oil and air to the nozzle 101, needle valvesare dispensed with and an adjustable valve member is provided for eachof the oil and air passages 128 and 129. Each comprises a plug 158longitudinallyadjustable in the passages by means of theirscrew-threaded relation at 159 with the casing. The plug extends througha stufling box 160 and has an outer slotted end 162 for engagement by ascrew-driver. The inner end of the plug terminates adjacent to the entryport and is notched as shown at 163. Varyingthe longitudinal position ofthe notch in front of the port 126 or 127 will vary the inlet opening.This construction is very advantageous, because as the plug is turnedthe edge of the notch serves to scrape the interior of the passage andto free it from collected dirt of any kind. Likewise, a half 1 turn onthe screw plug will reverse the notch,

compelling the oil or air to clean out any obstruction which may havelodged in the notch.

Referring to the air supply leading to the nozzle 101, it has been setforth that the oil line and the nozzle are cleared of oil on shuttingoff the oil, by letting airblow therethrough. For this reason there isprovided in the system a sufficient reservoir of air under compressionto supply thev necessary air for clearing out the oil line after the airpump has stopped. The reservoir for air is also provided for the purposeof eliminating pulsations of the reciprocatory pump above described,which might otherwise be undesirably effective at the nozzle. Referringnow to Figs..3, 4 and 5, an air reservoir 165 is preferably mounted onthe top plate 61 of the housing 40 directly over the air pump 47.Thusthe pump outlet 66 discharges directly into the. chamber 165 towhich the pipe 132 is connected as shown at 166 (Figs. 2 and 3).

The housing 40 contains suflicient lubricating oil to submerge the pump47, gears 42 and 43, etc. This arrangement and the pump constructionmakes it likely that the air pump will suck a slight amount of'oil anddeliver it with the air to the chamber 165.1 A constant air pressure isdesired in the air chamber in order to prevent a change in thedifferential oil regulating pressure at the nozzle. For this reason arelief valve is arranged to permit the escape of excess air, therebykeeping the pressure constant. Because of the likelihood of oilgathering in the bottom of the reservoir the air relief valve isarranged to blow from the bottom of the chamber to carry off theaccumulated oil. The valve is so arranged as to'blow ofi' into thehousing 40 to return the oil thereto.

Any desired structure may be used for the relief valve, but thefollowing is preferred. A hole 167 (Fig. 4) is tapped in the top 61 intowhich a valve casing 168 is threaded, the valve being contained withinthe reservoir 165. A chamber 169 having a seat 170 is formed upwardlyinto the valve casing.

Passages 171 communicate from the air reservoir 165 to the chamber 169.The passages 171 are arranged close to the level of the top 61 so thatthe liquid gathering in the chamber may flow into the valve. A valvehead 172 and stem 173 are provided, the latter extend ing through thevalve casing and having a nut 174 and spring 175 for yieldably holdingthe valve seated. The position of nut 174 of course determines theblow-oft pressure of the valve; Since it is desirable that this be fixedfor proper operation of the burner, the adjusting nut is located insideof the air reservoir. This insures that it will not be tampered withduring operation of the burner, and further because of itsinaccessibility it in effect compels competent service to make anadjustment. This is an important feature in domestic oil burners.

The ignition means is shown in Figs. 7 and 7 Within the sleeve 91 isinsulating material 176 which supports two conductors 177 and 178 havingsparking points 179. The sparking points are located in the path of theoil spray issuing from the nozzle 101.

A safety device is provided for assuring that the burner will berendered inoperative to supply oil to the combustion chamber when thereis a failure of combustion. Such means is operative through anaccumulation of unconsumed oil collected in a basin or covered chamber180 (Fig. 3) in the bottom of the bowl 15, the oil entering through ahole 180*. Into the basin 180 there is tapped a pipe 181 leading to anaxially tiltablc drum 182 (F gs. 1, 2, 3 and 3). The drum has apartition 183 therein so that oil may collect in but one side of thedrum behind the partition in order to overbalance the same to tilt it.An elongated slot 184 at the top of the drum into which the pipe 181-projects both permits and limits the tilting of the drum. A mercuryswitch 185 carried by the drum is suitably connected into a circuit,later to be described. for the purpose of stopping the operation of theburner.

'Other well known safety devices and appliances may be used inconnection with the foregoing as will appear more fully hereinafter inthe diagrammatic representation of the controlling circuits andmechanisms.

Control mechanism The control mechanism is herein shown as arranged tobe driven by-the burner motor, and preferably under the control of themain motor switch. An intermediate controlling nism, the latter beingdriven by the motor,

and being made responsive to a thermostatically controlled current.

The mechanical control is preferably made as a unit having a framecomprising the two opposing plates 195 and 196 (Figs. 8 to 11) connectedby a web-plate 197 at the forward side. At the rear of the unit there isa shaft 1 198 carrying a worm wheel 199. The gear 199 meshes with a worm200 (Fig. 3) on a shaft 201. Said shaft is connected by miter gears 202to a shaft 203 (Fig. 4) The latter is driven from the shaft 44through aworm wheel 204 meshing with a worm 205 formed on" the periphery of thecrank disk 45.

The shaft 198 drives the controlling'cam I shaft 206 which makes ahalf-revolution .to

. the control unit.

initiate combustion and a half-revolution to stop combustion. The shaft206 is preferably made tubular and surrounds the shaft 198,

being rotatably supported thereon. The

210 which is provided with a tooth-engaging 'part 211 designed to becaught by the ratchet wheel to turn the disk. A tension spring 212 tendsto swinw the dog into engagement with spring 212 is connected to boththe dog 210' and the plate 213 and tends to hold the plate 213 in aposition which may be described as advanced in the direction of normalrotation of the disk. The plate 213 carries a lug 216 projecting beyondthe periphery of the disk 208 so that during rotation of the disk a stopmeans, later to be described, may move the plate 213 from its advancedposition (Fig. 10) to its rear position (Fig. 11) relative to itscarrying disk 208, this motion being efl'ecv tive to move the dog 210out of engagement with the ratchet wheel, whereby to stop the rotationof disk 208. moving the dog includes a cam projection 217 on the plate213, which cam is moved into a position wherein it operates to raise thedog against the tension of its spring 212 into a position free fromengagement with the teeth of the ratchet wheel.

The present means for On the shaft 206 adjacent the disk 208 there isfixed a cam 218 (Fig. 8) having a circular periphery containing a recess219 (Fig. 11) which is positioned on the periphery ata point opposite tothe stopping lug 216. 'An

electric switch is incorporated into the device and so arranged as to beclosed in all positions of the cam 218-except one, at which position amovable part enters into the recess 219 to permit opening of the switch.Thus, when said movable 'part' is permitted by the remainder of themechanism to enter the recess, the switch is opened and the motorstopped.

Various constructions for mounting the i switch may be employed butthepreferable form comprises a plate 220 (Fig. 9) swinging on a fixed.pin 221 carried by the side plate 196. The plate 220 carries a mercuryswitch which is arranged in such a manner that it effects stopping ofthe main control shaft 198, in the present instance, it being connectedinto the motor circuit. The plate 220 carries a counterweight 222tending normally to swing the plate to open the motor switch 222 asshown in Fig. 10.' A linkage is connected to the plate to tilt itmechanically against the counterweight, said linkage being arranged tobe operated by the cam 218. The.

- bell crank 223224 also has a projecting heel 228 upon which pressuremay be placed to raise the cam roller 227 out of the recess 219 therebyto close the switch 222, closing the motor circuit and turning the camdisk 218 through the dog and ratchet device (which is thrown in asindicated in Fig. 10). The cam 218 therefore revolves and moves itsrecess 219 out from under the roller 227. The motor switch. cannot beopened until the cam disk has made at least a complete revolution toreturn the recess 219 into a position to receive the roller 227.

The shaft 225 is a rock shaft held between the cone bearings 230 and231, (Fig. 9) located respectively in the side plates 195 and 196. Tothe rock shaft is fixed a plurality of arms including an arm 232 (Fig.9) having an adjustable counterweight 233, a downwardly projecting heel234 arranged to press on the heel 228 of the bell crank lever 223224, aforwardly projecting arm 235 which carries an armature 236, and arearwardly extending stop arm 237. The tilting of the rock shaft 2251'slimited in one direction by the armature strikinga screw 236 adjustablyfixed in the frame.

The stop means heretofore alluded to and employed as an obstruction inthe path of the advancedly positioned lug 216 of the pawl and ratchetmechanism isa detent 238 (Fig. 10) depending loosely from the pivot pin221 (Fig. 11) and drawn rearwardly by a light spring 239 secured to apin 240 (Fig. 11)

on the side plate 196, the pin being right angular to provide a rearstop for the detent. The detent has a forwardly projecting lug 241 whichterminates near. the end of the stop arm 237 on the rock shaft 225.\Vhen the rock shaft 225 isnormally tilted I by its counterweight 233the arm 237 is lowered from its position in Fig. 11 to its position inFig. 10. and it is then out of the path through which the lug 241 mayswing about pivot 221. lock the detent 238 in fixed position. In itslocked position (full lines Fig. 11) it is a fixed stop means to causethrowing out of the dog 210, whereas in its unlocked position (dottedlines Fig. 10) it yields to permit the lug 216 to pass without throwingout the dog 210, the detent 238'swinging into the position as shown indotted lines 238 and 241 in Fig. 11.

Also upon release of the detent 238 through Thus the arm 237 may serveto the lowering of the stop arm 237, the dog 210 is automatically swunginto engagement with the ratchet wheel through the efl'ect of.' itsspring 212, the lug 216 and the plate 213 advance rotatively relativelyto the plate 208 through the action of tlie'spring 212, and the plate208 again rotates with the. main control shaft 198. In the initialadvance of the lug,

216 to its dotted line position 216 in Fig. 11, the detent 238 is swungahead of it into the dotted-line position indicated in Fig. 11 atposition (dotted lines Fig. 11) while the arm 237 is raised even thoughthe lug 216 has passed and thus. permits its return.

From the foregoing it will be. seen thatthere are certain positions ofthe arm 237 requisite for proper operation of the device. For a varietyof reasons this is preferably controlled by an electromagnet 242 (Figs.9, 10 and 11) acting on the armature 236 carried by the rock shaft 225.Current to the magnet is in part controlled by a switch device carriedon the'cam shaft 206 and in part by thermostatic means to which theburner is made responsive.

Assuming the motor 25 to be stopped and the burner idle, thecounter-weight 222 holdsthe parts in the'position shown in Fig. 10 withthe cam roller 227 in the cam recess 219. Energizing the magnet 242 willcause the heel 234 to act on the heel 228'and thereby to 7 close themotor switch 222 and thus start the shaft 198as heretofore described.The dog being located at the lower side of its orbit,

the cam shaft 216 will rotate half a revolution until the lug 216 meets.its detent 238. During this period any program of operations requisiteto initiate combustion is carried out, the several operations beingperformed in proper sequence through the action of the rotating camshaft 206. In order to stop the cam shaft the arm 237 must be in lockingposition as regards the detent 238 at the time when the lug 216 meetssaid detent; and said arm 237 must be maintained in its raised lockingposition during the time in which the clutch is to be kept thrownout,that is while the burner is operating. The mere dropping of the arm 237out of locking position allows the clutch to be thrown in automaticallyand the cam shaft again rotates half arevolution, during which suitablestopping operations of the burner parts may be effected in propersequence by the rotation of the cam shaft. lVhen the recess 219 of themotor switch cam 218 comes around to the cam roller 227, the switch willopen by the dropping of the roller 256 (Fig.

ma net being so arranged that it is energized.

whgn heat is demanded and deenergized when no heat is demanded. In thepresent instance there is employed a room thermostat of the well knowntype wherein one circuitis closed when the room becomes too' cold andanother circuit is opened when the room hecomes too hot. Thus, above amaximum temperature no circuit is closed in the thermostat; between thedesired upper and lower limitsof temperature control one circuit isclosed in the thermostat; and below the minimum desired temperature,both circuits are closed in the thermostat. Such a thermostat isindicateddiagrammatically in Fig. 13 in which L and H representadjustably fixed contact .points corresponding to the lower and highertemperature limits desired, and to which independent circuits areconnected indent-ified respectively as cold and hot. A common wire J isconnected to a thermal expansive element 245 which is electricallycommon to both circuits. The element is in efiect split at the movableend forming two branches which make successive contact with the contactpoints L and H as the temperature varies. The three conditions are.respectively indicated in (a), (b) and (c) in Fig. 13 corresponding tothe room being (a) too cold, (1)) properly tempered between the desiredlimits, and (a) too hot.

In the diagram Fig. 14, the thermostat is generally designated 245, itbeing understood that it partakes of the character of the thermostatdescribed with reference to Fig. 13

and having three possible internal conditions.

There is provided a low voltage electrical source indicated at 246,which in the present instance is'a six volt source, connected from oneterminal by wire 247 to one side of the electromagnet 242. Wire 248leads from the magnet to the J or common wire of the thermostat. On thecam shaft 206 (Figs. 8 and 9) there is an insulating drum 249 aroundwhich is a continuous metallic band 250. The band has alternate anddiametrically opposite lateral projections 251 and 252 arranged so thatone of them, 251, is on top when the recess 219 of the motor switch camis on top. In the diagram (Fig. 14) the dotted line position of the ringlugs indicates the position of the ring after a half revolution of thedrum. Three spring contacts 253, 254, and 255 respectively engage withthe ring 250 and the lugs 251 and 252, these being securely fastened toan insulating strip 9) on the front connecting frame plate 197. Screws257, 258 and 259 are used contact bar 254 t'o the cold circuit L of thethermostat; a wire 261 connects the hot circuit H of the thermostat andthe contact bar 255; and a wire 262 connects the source 246 and themiddle contact bar 253."

Diagram Fig. 14 represents in full lines the control device in therunning position of the burner (Fig. 11) the electromagnet 242 beingenergized because contact H in the thermostat is closed and the circuittherethrough is completed by wire 262, contact bar 253,-ring 250, lug252, bar 255, wire 261, thermostat contact H, common wire 248,electromagnet 242, wire 247, source 246. \Vhen the room temperature goesover the upper temperature limit, contact I-I opens whereupon themagnet. 242 is deenergized, the arm 237 drops through the dropping ofthe counter-weight 233, and the clutch automatically throws itself intoengaging position to turn the cam shaft 206 including the drum 249 whichcarries the contacts 251 and 252. The ring and lugs on drum 249 move tothe dotted line position of Fig. 14. Just prior to the recess 219arriving at the cam roller 227 the contact bar 254 wipes the lug contact251 but no circuit is completed through the magnet because contact L inthe thermostat is open. Therefore the arm 237 remains down and the camroller drops into the recess 219 to open the motor switch 222 and thusstop the entire apparatus. This condition continues until the lowerlimit of room temperature is reached. Thereupon closure'of the contact Lenergizes the magnet 242 and rocks the shaft 225, to close the motorswitch, raising the roller 227 out of its recess 219 as an incident tothe operation. This starts the motor and thus sets the cam shaft 206 inrotation, said cam shaft again causing the required starting operationsto be performed according to the mechanisms associated with the camshaft. After a slight rotation from the starting position the lug 251recedes from the bar 254 and the magnet 242 is de-energized, but thisdoes not take place until the recess in cam 218 has moved away from theraised roller so that the cam periphery holds the roller up andmaintains the switch in closed position. As rotation continues theclutch lug 216 approaches the detent 238. The magnet being de-energized,the arm 237 is not in a position to lock the detent. However,'the lug252 is arranged to make contact with the bar 255 prior to the arm 266pivoted in the frame of the control device at 267. The arm 266- carriesat its outer end a cam roller 268 which rides on a cam 269 rigid withthe cam shaft 206. One

portion 270 of the cam surface is substantially radial, which permitsthe cam roller 268 to drop and the oil valve to open suddenly. The camsurface 270 is placed so that the oil valve opens just prior to thedisengagement of the clutch. The cam 269 has an inner concentric camsurfaceor dwell 271 which permits the cam shaft to turn approximatelyone-eighth of a revolution in its burner-stopping operation withoutaffecting the valve, after which a rise in the cam surface at 272 raisesthe roller to close the valve. The closing action of the valve iscompleted in about one-eighth of a revolution, after which the cam turnsfor approximately one-fourth of a revolution before the power is shutoff through the motor switch 222. Thus the air pump continues inoperation after the oil has been shut off and assures the blowing out ofthe oil line and nozzle, as heretofore described.

The supply of current to the sparking points 179 is primarily controlledby the motor switch 222, as indicated in Fig. 12, the supply of currentto the igniter being cut of]? when the motor switch is opened. However,since the character of spark ordinarily employed is such as to interferewith the use of a radio receiver, means is provided for cutting out thespark when it is not necessary and. for automatically connecting it whenit is required for proper operation of the burner.

The ignition circuit includes a mercury switch 280 (Fig. 9) which iscarried by a lever 281 (Figs. 8, 9, 10 and 11) pivotally mounted on aboss 282 secured to the side wall 195. A screw 284 forms the pivot, anda spring 285 acting on a washer 286 places frictional pressure on thelever 281. The lever 281 extends forwardly and projects through thecasing so that one may raise said end of the lever to open the switch.Friction holds the lever in raised position to maintain the switch open.On the rear end of the lever 281 is a downwardly extending arm 287carrying a cam roller 288 arranged to be moved by a cam 289 on the camshaft,

206. The cam 289 is similar to the cam 218 having one cam recess 290(Fig. 11) arranged to lie at the top in the operat ng osition of theburner, and hence diametrical y opposite the recess 219 of the motorswitch cam 218, which lies at the top in the idle position of theburner. Thus while the burner is in operation the notch 290 is sopositioned that the ignition switch 280 may be manually opened, that is,roller 288 may enter the recess 290 of cam 289. Subsequent rotation ofthe cam 289 when the burner is being stopped will close the switch sothat the ignition system will be effective in a subsequent startingoperation.

A spring pressed plunger 291 (Fig. 3) on the housing 40 is arranged formanual depression of the armature 236 when the magnet is not energized.This enables one to start the burner independently of the thermostatcircuit which, of course, will control the further action of the burnerafter being so started.

The remaining electrical devices and circuits of the oil burner areindicated in Fig. 12. The boiler or heater with which the burner is usedis preferably provided with a well known safety control device indicatedgenerally at 301 which is effective upon exccssive steam pressure orexcessive rater temperature to shut off the burner independently of theroom thermostat. This device is represented as containing a mercury tubeswitch 302 adapted to open on excessive heat. The mercury tube switch185 is also arranged to open on accumulation of oil in the drum 182.Both these switches, together with the motor 25 and the cam operatedswitch 222, are connected in series in the order named to a power source303 which in the present instance is 110 volt alternating current. Thespark ignition is obtained through an induction coil having the primarycoil 304 and secondary coil 305 from which the wires 306 lead to thespark terminals 179. One side of the primary coil is connected by wire307 to one side of the motor 25 and the other side is connected by wire308 to the other side of the motor through the optionally cut-out andautomatically cam-closed ignition switch 280. The low voltage source 246of Fig. 14 of the thermostat circuit as above mentioned is a six voltcircuit obtained from a transformer connected to the main AC line. Inthe present instance two similar transformers 309 are used and areconnected parallel, this arrangement being chosen so that when a 220volt source is available the two transformers may be connected inseries. The transformers are connected by wire 310 to one side of thepower source 303, and by the wire 311 to the other side at a pointbetween the boiler control switch 302 and the oil control switch 185.This point is chosen for connection of the transformer circuits becausein the instance when the heater becomes excessively hot while the roomthermostat is still demanding heat, the boiler control switch 302 cutsoutthe motor and also the control current.

Assuming the parts to be in the position shown in Fig. 11, opening ofthe switch 302 cuts out the transformers, and thus deenergizes themagnet 242, so that the clutch lug 216 is released and the clutch thrownin.

However, the cam shaft 206 remains at rest,

motor begins running and turns the cam shaft 206 through ahalf-revolution, thus bringing the recess 219' into register with theroller 227. If'the room is still cold, there is a circuit through themagnet 242 as follows Source 246 (the transformers), line 262, bar 253,ring 250, lug 251, bar 254, wire 260, contact L, wire 248', magnet 242,source 246. Hence the magnet will prevent the roller 227 from droppinginto the recess 219, and the motor will continue running. The cam shaft206 will therefore make another half-revolih tion to complete a cycle'during which the starting operations are initiated. This is calledrecycling. In the initial stage of the recycling, after'the lug 216 haspassed its unlocked detent 238, the electromagnet circuit is broken sothat arm 238 may return to normal obstructing position. Just prior tothe completion of the cycle of cam revolution a circuit is establishedthrough lug 252 and contact H in the thermostat to energize the magnet,to lock the detent, and thus to throw out the clutch.

The above operation has been described with reference to the operationof the boiler safety switch 302, but it is obvious that the sameoperation will also take place when the source of power 303 fails. Thewhole arrangement is thus sufficient to protect the burner from ahazardous condition on failure of power, because on return of power theburner,

although stopped in the operative osition by the failure, will berecycled throug its starting stage to ensure that combustion isinitiated.

The function of the control mechanism to cut off the burner when thereis a break in the thermostat circuit should be clear from the foregoingdescription. Under such conditions the magnet cannot be energized, theclutch cannot be thrown" out and the cam shaft will always rotate untilthe motor switch cam roller 227 drops into its cam recess 219 whereuponthe motor will stop. Nothing can operate to start the motor except theenergization of the magnet, or the manual depression of the plunger 291.In the latter instance the cam shaft will turn for one cycle and thenstop automatically.

Although the motor control mechanism has been shown specifically asmoved directly by the motor 25, it is to be understood that thearrangement is not limited to such a driving means. The motor is undercontrol of the motor switch, hence the motive power for the controlmechanism may be regarded as under the control of said switch. For thisreason the driving shaft 198 is to be considered broadly as a secondarysource of power, or

rather as a source of motive power for the control mechanism, and theclutch mechanism is to-be considered broadly as a power cut-01f betweensaid source and the control mechanism, said power cut-off having apower-onand a power-01f position corresponding respectively to throwingin and out the dog of the clutch.

The burner is adapted for 'two types of installation, one wherein theoil is pumped,

and the other wherein air pressure is utilized to force oil from a tank.The oil-pumping system has been describe'd'only generally as includingthe oil pump 41, but it involves further an intake pi e 315 (Figs. 1 and3),

an outlet pipe 316 igs. 1,2 and 3), and a constant pressure relie orby-pass valve 317 of well known construction, which delivers the excessoil supplied by the pump through a return flow ipe 318 back to theinitial source. Oil under the pressure at which the valve 317 is setflows through the pipe 131 as heretofore described. The contlnuous flowof oil obtained by this arrangement prior to the opening of the oil lineto the nozzle allows all air bubbles to be removed from the oil streamso that the nozzle line upon opening of the valve 125 can be tapped intoa completely fille'd air-free oil-flow. This prevents delivery of amixture of oil and air to the nozzle which causes an undesirablesputtering. and frequently an extinguishment of the flame within theheater.

When the oil pump is not to be used, the air chamber 165 on top of theburner housing may be dispensed with, if desired. Such a modified use ofthe apparatus is shown in Fig. 1

wherein 61 represents the top of the housing, heretofore described withre erence to Figs. 4 and 5. The air delivered from the pump outlet 66 iscarried directly by a conduit 320 to an air chamber 321 on a fuelpressure tank 322. An oil line 323 runs from the bottom of the tank tothe oil valve casing 125. An air line 324 runs from the chamber 321 tothe valve structure 125. This construction prevents pulsations of theair pump from being felt at the nozzle and also allows any oil which maybe pumped with the air to be discharged into the tank and mixed with thefuel oil. A relief valve 325 is also placed on the air reservoir 321 tomaintain the air pressure therein constant in the same manner as desiredwhen the air chamber 165 is employed.

The operation of the apparatus shown in all of the views except Fig. 1maybe briefly summarized as follows, assuming that the burner is idle,the control mechanism being in the position shown in Fi 10, and theignition switch 280 being he (1 closed by the cam 289: When thetemperature in the room in which the thermostat 245 is located fallsbelow a predetermined minimum, the electrorelief or byzpassvalve 317;the air pump begins to'buil up air pressure in the reservoir 165 (airflowing through the air line 122, and

'a negligible quantity of air escaping through the oil line); and thecam shaft 206 begins to turn. By the time the cam shaft has nearlycompleted a half revolution, the air pump has built u suflicientpressure in the reservoir 165, an the roller 268 (Fig. 10) drops ontothe dwell 271 of the oil valve cam 269, thereby opening the oil supplyport 141, whereupon oil flows to the nozzle, where it is ignited by theare between the points 179. As the cam shaft 206 completes a halfrevolution the clutch is thrown out, thus leaving the control mechanismin the position shown in Fig. 11. By reference to Fig. 11, it will beseen that the dog 210 lies on the projection 217 and that the tension ofthe spring 212 (which is stretched between the dog 210 and the plate213) holds the lug 216 on said plate pressed against the detent 238. lVhen the temperature in the room containing the thermostat 245 rises tothe predetermined maximum, the electromagnet 242 is deener gized,whereupon the counterweight 233 lifts the armature 236 and swings thestop arm 237 down below the arm 241 of the detent 238, whereupon thespring 212 is permitted to turn the plate 213 clockwise (as viewed inFig. 11) to withdraw the lug 217 from beneath the dog 210, the detent238 yielding tothe right to allow of such movement of the plate 213.Shortly after the cam shaft 206 has commenced to turn by reason of thethrowing in of the dog 210, the cam surface 272 of the cam 269 closesthe oil supply port 141 and allows air to flow through the port 146, theair passage 148 and the air port 142 to the oil line until the pressurein the reservoir 165 is reduced to atmospheric pressure, thus blowingout all the oil in the oil line 121 and the nozzle. As the cam shaft 206completes a half revolution the recess 219 arrives under the roller 227,whereupon the weight 222 places said roller in said recess and tilts themotor switch 222 into the open-circuit position, whereu on the motorstops, leaving parts in the position shown in Fig. 10.

With the form of oil supply means shown in Fig. 1, the operation issubstantially the same as that just described. \Vhether one or the otherform of oil supply means is used, the opening of the oil valve 149 (Fig.6) is timed to occur when suflicient air pressure has been built up inthe reservoir 165 or 321, as the case may be.

It will be seen that the control mechanism herein disclosed is of suchcharacter that the necessary program of operations required in throughin proper order and time relation.

The arrangement herein shown of the fuel discharge means, the combustionbowl and the air supply means is claimed in a divisional applicationSerial No. 90,452, filed February 25, 1926.

I .claim as my invention:

1. A control device adapted for operation by a motor operated oil burnerfor the purpose of controlling said burner comprising, inv combination,a power shaft arranged to be operated directly by the burner motor, acontrol shaft, a clutch connecting said two shafts, means underelectrical control and positioned to throw out said clutch, mean'spositioned on said control shaft to cause said first means to disengagethe clutch at a predetermined position of said control shaft, a switchto control the motor of the burner, means on said control shaftpermitting free operation of said switch in one position of the shaftand compelling closing of said switch in other positions of the shaft,said opened position of the switch occurring while the control shaft isopcratively connected to the burner through said clutch, means tendingnormally to open said switch whereby it opens automatically whenpermitted for the purpose of stopping the motor and the control shaft, aroom thermostat, and means operatively arranged to close the switch fromsaid thermostat when heat is required, whereby the control shaft rotatesto a position to throw out the clutch, the switch meanwhile being heldin closed position, said electric clutch-coutrolling means beingoperatively associated with the thermostat to permit engagement of saidclutch when heat is not required whereby the control shaft rotates topermit opening of the switch by the means tending normally to open. theswitch. I

2. In combination, a motor operated oil burner, a thermostat, amechanical motive device arranged to move for starting the burner intooperation, said device being also arranged to move for stopping theburner, said device including self-stopping mechanism, a clutchconnection from the burner to the motive device, said self-stoppingmechanism being operative upon the clutch to disengage the same, saidmechanism being affected by the thermostat to throw in said clutch tostart the device on its burner stopping motive action, an electricswitch controlling the burner motor and arranged to be operated by themotive device to stop the burner motor, said switch being arranged alsoto be closed-by the thermostat to start the motor.

3. In combination, an oil burner motor, a thermostat to control thestarting and stopping of the motor, a control mechanism operable toapredetermined extent in starting the motor and in stopping the motor,said mechastarting or stopping the apparatus is carried rect control ofthe electrically nism including a. motor switch, the position of whichis in part controlled by said mechanism, a power connection between themotor and the control mechanism, said thern'iostat being arranged toclose the switch to start the motor and the control mechanism, and beingfurther arranged to control the power connection for stopping andstarting the control mechanism during operation of the motor.

4. In combination, an oil burner motor, a

thermostat to control the starting and stopping of the motor; a controlmechanism operable to a predetern'iined extent in starting the motor andin stopping the motor, said mechanism including a switch to control themotor, the position of said switch being controlled by the position ofthe control mechanism, a power connection between the motor and themechanism, said thermostat being arranged to start the motor initiallyto move the control mechanism through said power connec-, tion, andbeing further arranged to control the power connection for stopping andstarting the control mechanism during operation of the motor.

5. An automatically controlled oil burner comprising, in combination, anelectrically operated burner, a mechanical controlling motive device forthe burner, and a motive power source for said device. under thedioperated burner so as to be on and olt' with said burner. said deviceincluding a control means for said source operative to cut in and outsaid source during operation of the burner. a thermostat responsive tothe burner. and means responsive to said thermostat for controlling saidpower controlling means and also the electrically operated burner.

(i. In combination, an oil burner motor. a switch to control said motor.a thermostat, a control mechanism operative upon the switch to controlthe motor and to institute starting and stopping operations of theburnor said motor being responsive to the thermostat for starting themotor. and a source of power for the control device. said source beingdependent upon the power controlled by the main motor switch. and meansactuated by the control mechanism responsive to said thern'iostat tocontrol the transmission of power from said source to the mechanism.

7. A thern'iostatic control for a rotary control device movable in acycle between two positions for starting and stopping an oil burnercomprising, in combination. a three wire two circuit thermostat arrangedto have both circuits closed below a minimum temperature, both circuitsopened above. a maximum temperature, and a certain circuit closed at theintervening temperatures, an electromagnet and an electrical sourceconnected in' Serise with the common wire of the thermostat circuits, aswitch device ope 'ated by the rotary device to shift the connection ofthe free terminal of the source to one or to the other of the thermostatcircuits, the arrangement being such that upon the temperaturedecreasing to the minimum the magnet is energized, whereupon movement ofthe rotary device to its second position operates upon the switch meansto shift the electromagnet to the other circuit, whereupon the magnet isagain energized while the device occupies its second position and untilthe temperature reaches a maximum, whereupon de-energization of themagnet causes the parts to assume the initially described position.

8. In combination, a thermostat, an electromagnet energized by currentpassing through said thermostat when heat is required to raise thetemperature of the thermostat to a predetermined degree, an oil burnermotor arranged to be controlled by I the thermostat, an electric switchfor the motor, said switch being arranged to be closed on energizationof the magnet, a control mechanism to institute starting and stoppingoperations of the burner including the opening of said motor switchduring the period of de-energization of the magnet, said mechanismhaving means therein to hold.- said switch closed and to open itautomatically at a predetermined position of the mechanism, a powertransmitting clutch between the motor and said mechanism, and meansoperable during energization of said magnet to effect disengagement ofthe clutch at a second predetermined position of the control mechanism.

t). In combination, a thermostat, an electromagnet energized by currentpassing through said thermostat when heat is required to raise thetemperature of the thermostat to a predetern'iined degree, an oil burnermotor arranged to be controlled by the thermostat, an electric switchfor the motor, said switch being arranged to be closed on energizationof the magnet, a control mechanism to iustil ute starting and stoppingoperations of the burner including the opening of said motor switchduring the period otdeenergization oi the magnet, said mechanism havingmeans therein to hold said switch closed and to open it automatically ata predetermined position of the mechanism. a power transmitting clutchbetween the motor and said mechanism. and means operable duringenergizatipn of said magnet to ellect disengagement ot the clutch at asecond predetermined position of the control mechanism, and means in thecontrol device to break the circuit to the magnet for an interval durinthe movement of the mechanism from the set ond to the tirstpredetermined position. I it). In combination, a thermostat, anelectromagnet energized by current 1' assing through said thermostatwhen heat is required to raise the temperature of the ther loo

